The present invention relates to a novel semiconductor device and a novel circuit board that are used for efficient connection of a bare chip semiconductor element to a circuit board.
In general terms, semiconductor elements, such as IC, are formed in great numbers on a wafer and cut into respective chips, each of which chips is connected to a circuit board. With an increasing number of ICs formed on a chip, the number of electrodes formed on the chip also increases, which in turn requires the shape and arrangement pattern of the electrodes to be finer and more narrow-pitched. In addition, a chip and a circuit board are not connected by a wire any more but by mating a conductor part of the circuit board to an electrode part of the chip (e.g., flip chip bonding). Alternatively, a naked chip may be mounted on a substrate (bare chip mounting).
When mating a conductor of the circuit board to an electrode of the chip, as mentioned above, an anisotropic conductive film may be used between the chip and the circuit board.
An anisotropic conductive film (hereinafter to be abbreviated as ACF) is anisotropic in terms of conductivity, because it is conductive in the direction penetrating the two sides of a film and insulating in the direction of expansion of the film surface.
When a chip is mounted via an ACF, the chip, the ACF and a circuit board are superimposed for alignment, and they need to be bonded simultaneously. However, alignment of these three members requires such a high manipulative technique that a simple chip mounting apparatus cannot be used. Consequently, the productivity of the mounting process becomes low.
It is therefore an object of the present invention to solve the problem in bonding the above-mentioned three members, thereby to improve productivity of the mounting process for connecting a semiconductor element and a circuit board via an anisotropic conductive film.
The present invention is characterized by the following embodiments.
A semiconductor device comprising an anisotropic conductive film and a semiconductor element, wherein the film is bonded to the element on the side comprising an electrode, such that the electrode is electrically connectable to an external circuit via a conductive path in the film.
(Embodiment A)
A semiconductor device comprising an anisotropic conductive film and a wafer carrying plural semiconductor elements thereon, wherein the film is bonded to all the semiconductor elements on the side comprising electrodes, such that the electrodes are electrically connectable to an external circuit via conductive paths in the film.
(Embodiment B)
A semiconductor device comprising a semiconductor element and an anisotropic conductive film, wherein an electrode of the element is bonded to or in contact with an end of a conductive path of the film, and at the contact point, the electrode is covered with aluminum and the conductive path is covered with gold, or the electrode is covered with a barrier metal and the conductive path is covered with solder.
(Embodiment C)
When the contact part or bonding part on the side of the conductive path is to be plated with gold, a nickel plating is preferably applied beforehand as the base plating.
A circuit board for mounting a semiconductor element, which comprises an anisotropic conductive film and a circuit board, wherein the film is bonded to the. circuit board on the side comprising the circuit, such that the circuit board is electrically connectable to the element via the film.
(Embodiment D)
A circuit board for mounting a semiconductor element, which comprises an anisotropic conductive film and a circuit board, wherein the circuit board is bonded to or in contact with an end of a conductive path of the film, and at the contact point, the circuit is made of solder and the conductive path is made of gold.
(Embodiment E)
In the present invention, the anisotropic conductive film comprises a film substrate made of an insulating resin and conductive paths. The conductive paths comprise metal conductor wires that are insulated from each other and that penetrate the film substrate in the thickness direction of the film. Moreover, the circuit board comprises an insulating substrate and a circuit for mounting. The circuit has a conductor pattern for connection with electrodes and is formed on one side of the substrate.